Make sure you are happy with everything that goes into the house. Don't let the builder cut corners. Make sure the subs do good workmanship. Check out the tile people, countertops/backsplash installers, painters, finish carpenters. You don't want to end up with tile installed poorly and you will always be unhappy with it.

Don't cut corners on doors, windows, floor coverings. toilets, fixtures, lighting, etc. If you have to save money then you have to buy cheaper stuff. But don't do it unless you have to. Try to at least get what you like.

Styles are constantly changing. You should do some homework and look at what builders in your area are doing that is the latest in style and design. Don't go with ten year old styles and designs because you like them. Try to go with the latest stuff out there. That way your house won't be outdated as fast.